Steering wheel having airbag apparatus

ABSTRACT

A steering wheel of the present invention has an airbag apparatus. The airbag apparatus has a pad for covering the airbag, and the pad has a plurality of doors that can open. Each door opens around a hinge as a rotation center. The hinge is located below an outer periphery of the pad. That is, an area of the door itself can widely be secured, and the door can open as wide as possible. A switch operating portion is disposed in an area other than the door, but of a boss or a spoke that is not covered with the door when it opens. When doors open around the hinge as the rotation center, the doors are disposed in the three spaces between the spokes. The opened doors are disposed smoothly in the three spaces between the three spokes without interference with the switch operating portion. A widely opening state of each door can stably be secure.

[0001] The present application claims priority to Japanese patentapplication of Fujita et al, filed Sep. 26, 2000, No.2000-293164, andJapanese patent application of Fujita et al, filed Sep. 26, 2000,No.2000-293166, the entirety of each is hereby incorporated into thepresent application by this reference.

BACKGROUND OF THE INVENTION

[0002] 1. Field of the Invention

[0003] The present invention relates to a steering wheel for a vehiclehaving an airbag apparatus. More particularly, the invention relates toa steering wheel having an airbag apparatus and in which switchoperating portion of a function part is disposed. Examples of thefunction part are drive monitor switch, constant-speed runningapparatus, audio equipment, air conditioner equipment, navigationsystem, telephone, shift change and the like.

[0004] 2. Description of Related Art

[0005] Conventionally, a steering wheel having an airbag apparatus isknow in Japanese Patent Applications Laid-open No.100907/1998 andNo.11246/1999. The airbag apparatus comprises an airbag, an inflator, apad and a bag holder. The airbag is folded such that the airbag canexpand. The inflator supplies expansion gas to the airbag. The padcovers the folded airbag. The bag holder holds the airbag, the inflatorand the pad, and is connected to a steering wheel body.

[0006] The pad includes a door that is pushed by the expanding airbagand opened. The door is provided at its periphery with a to-be rupturedportion, and is provided at its portion of an outer periphery with ahinge. The door is pushed when the airbag expands to rupture the to-beruptured portion, and opens around the hinge as a rotation center.

[0007] In these days, it is increasingly required to dispose switchoperating portions for the function part that are drive monitor switch,constant-speed running apparatus, audio equipment, air conditionerequipment, navigation system, telephone, shift change and the like onthe pad of the boss or the spokes near the boss. These switch operatingportions are constituted such that they can be operated from above. Thatis, the switch operating portion comprised operation button or operationlever operated by being pushed downward or swung. In order to facilitatethe operation of the switch operating portion, the switch operatingportion is disposed upward such that its operating surface approaches aring surface. The ring surface is the plane formed by an upper surfaceof a ring when the steering wheel is viewed from a directionperpendicular to a steering shaft.

[0008] However, when the airbag is developed and expanded when a driveris close to the steering wheel, it is necessary that the airbag does notapply a partial pushing force to the driver. For this purpose, it ispreferable to develop the airbag widely at initial stage of expansionand to inflate the airbag toward the driver. At that time, if the doorof the pad interferes with the switch operating portion uselessly, thedoor can not open widely. That is, the airbag at its initial expandingstage can not be developed widely.

[0009] In the present specification, the upper-lower, front-rear andright-left directions are based on the steering shaft when the steeringwheel is mounted to the vehicle unless otherwise stated. That is, theupper-lower direction in the present specification is a verticaldirection along the axial direction of the steering shaft. Thefront-rear direction in the present specification is the front and reardirection (a longitudinal direction) of the vehicle along a directionperpendicular to the axis of the steering shaft when the steering wheelis steered straightly.

SUMMARY OF THE INVENTION

[0010] The present invention solves the above problems. That is, thepresent invention provides a steering wheel having an airbag apparatuscapable of widely open a door of a pad even if a switch operatingportion is disposed.

[0011] A first steering wheel having an airbag apparatus of the presentinvention has the following structure. That is, the steering wheelcomprises a ring grasped at the time of steering, a boss disposed on acenter of the ring, three spokes for connecting the ring and the boss,and a space between the spokes. The steering wheel also includes, asconstituent parts, a steering wheel body, the airbag apparatus disposedon the boss, and a switch operating portion that can be operated fromabove. The switch operating portion is disposed at least one of the bossand the spoke. The airbag apparatus comprises an airbag folded such thatthe airbag can expand, an inflator for supplying expansion gas to theairbag, a pad for covering the folded airbag. Further the airbagapparatus comprises a bag holder connected to the steering wheel bodyfor holding the folded airbag, the inflator and the pad. The padincludes three doors such that one opening through which the airbagprojects can be formed in a center of the pad. Each of the doors isprovided at its periphery with to-be ruptured portion. And hinges aredisposed on the periphery side of each of the doors. The door is pushedby the airbag when it is expanded and the to-be ruptured portion isruptured, the door opens around a hinge disposed on the side of an outerperiphery of the pad as a rotation center. A pad is held against the bagholder in the proximity to the hinge of each of the doors. The hinge ofeach of the doors is disposed at a position near the space between thespokes, and on the side of an outer periphery of the pad that is lowerthan an portion above a holding portion by the bag holder near thehinge. Each of the doors is disposed in the three spaces between thespokes when the door opens around the hinge as a rotation center. Theswitch operating portion is disposed on an area other than the doors andon the boss or the spoke that is not covered with the door when itopens.

[0012] According to the first steering wheel of the present invention,if the airbag is expanded to push the three doors of the pad, each ofthe doors of the pad ruptures the to-be ruptured portion there aroundand opens around the hinge as the rotation center.

[0013] At that time, the hinge of each door is disposed at a positionnear the space between the spokes and at the side of the outer peripheryof the pad lower than a portion above the holding portion by the bagholder near the hinge. Thus, the door opens around the hinge as therotation center at a position lower than the outer periphery of the pad.That is, the door can secure the wide area of its own and can open aswide as possible.

[0014] If the hinge of the door is disposed above the holding portion bythe bag holder, the area of the door itself becomes narrow. Thus, thedoor can not open widely.

[0015] Further, the switch operating portion is disposed in an areaother than the doors, but of a boss or a spoke that is not covered withthe doors when they open. When doors open around the hinge as therotation center, the doors are arranged so as to be disposed in thethree spaces between the spokes. The opened doors are disposed smoothlyin the three spaces between the three spokes without interference withthe switch operating portion. A widely opening state of each door canstably be secure.

[0016] Therefore, according to the first steering wheel having theairbag apparatus of the present invention, even if the switch operatingportion is disposed in an area of the boss or the spoke, the doors ofthe pad can widely open. Thus, in the first steering wheel, the initialexpanding airbag can widely develop.

[0017] It is preferable that the to-be ruptured portion at a portion ofthe adjacent doors is substantially T-shape as viewed from above. Thatis, the to-be ruptured portion has a lateral line portion disposed inthe right-left direction and a longitudinal line portion extendingrearward from a substantially central portion of the lateral lineportion. The left and right opposite ends of the lateral line portionare directed to disposition directions of the front left and rightspokes of the spokes, and a rear end of the longitudinal line portion isdirected to a disposition direction of the rear spoke in the spoke. Withthis steering wheel, the following working effect can be obtained.

[0018] That is, in the three spokes type steering wheel, the front spaceis set greater than rear left and right spaces so that the measuringinstruments of the instrument panel can easily be seen. Therefore, ifthe to-be ruptured portions adjacent to the doors are substantially T inshape, the front door in front of the lateral line portion of the to-beruptured portion has a greater area. The left and right doors divided bythe rear longitudinal line portion that is behind the lateral lineportion have a smaller area. As a result, shapes of the front, left andright doors can easily be fit to the front, left and right spaces inwhich the doors are accommodated when they opens. That is, the shapes ofthe front, left and right doors can easily be set.

[0019] Further, the pad may be provided with the following ceiling walland side wall. The ceiling wall is disposed on an upper portion of thepad and has the doors and the to-be ruptured portion. The side wallextends downward from the ceiling wall and is disposed in the verticaldirection such that the side wall can be connected to the bag holder. Aremaining portion of the to-be ruptured portion except adjacent portionswhich adjoin the doors is disposed close to an inner surface of the sidewall of the ceiling wall and substantially along the side wall. Withthis pad, the following working effect can be obtained.

[0020] That is, the side wall of the pad increases the thickness of theceiling wall. Then the remaining portion of the to-be ruptured portionexcept adjacent portions of the doors approaches the inner surface ofthe side wall portion which increases the thickness of the ceiling wall.Therefore, stress concentration is prone to be generated in theremaining portions. Further, the remaining portions are disposed alongthe general portion of the side wall. Therefore, the remaining portionsrupture easily along the general portion. As a result, the to-beruptured portion easily ruptures and the doors smoothly open.

[0021] Further, it is preferable that three clots when the airbag isfolded are disposed below the front, left and right doors. With thisstructure, when the airbag is developed and expanded, the front, leftand right doors are reliably pushed by the folded portions disposedbelow, and the airbag can smoothly open.

[0022] A second steering wheel having an airbag apparatus of the presentinvention has the following structure. That is, the steering wheelcomprises a ring grasped at the time of steering, a boss disposed on acenter of the ring, and a spoke for connecting the ring and the boss.The airbag apparatus is disposed on an upper portion of the boss. Theairbag apparatus comprises an airbag that is folded such that it can beexpanded, and a pad for covering the folded airbag. The pad includes adoor that is pushed and opened by the expanding airbag. A switchoperating portion is disposed below the door when it is opened. Theswitch operating portion is disposed in a non-limited region where anopening-completion state of the door is not limited for the door thathas completed its opening operation.

[0023] According to the second steering wheel of the invention, if theairbag is expanded to push the door of the pad, the door opens, and theairbag projects from the pad. At that time, the switch operating portionis disposed in the non-limited region where the opening-completion stateof the door is not limited to the door when it has been opened. Thus,the door can complete its opening in a widely opened state withoutlimited by the switch operating portion.

[0024] Thus, according to the second steering wheel having the airbagapparatus of the present invention, even if the switch operating portionis disposed below the pad door when the door opens, the pad door can beopened widely. Thus, in the second steering wheel, the airbag in itsinitial expanding state can be widely developed.

[0025] This second invention is not limited to the three spoke typesteering wheel, and the invention can also be applied to two or fourspoke type steering wheel. The number of the doors of the pad is notlimited to three, and one or more doors may be provided.

[0026] In the second steering wheel, it is preferable that the switchoperating portion is disposed in the non-limited region when the switchoperating portion is pushed and moved by the door when it opens. Withthis structure, in a normal state before the door opens, the switchoperating portion can be disposed near the ring surface located upperposition. Thus, in the second steering wheel, even if the switchoperating portion is disposed below the pad door when it opens, a widelyopening state of the door can be secured, and the operability of theswitch operating portion becomes excellent.

[0027] In this case, when the switch operating portion is pushed andmoved by the door, the switch operating portion may be lowered into thenon-limited region.

[0028] When the switch operating portion includes an operation buttonthat is pushed down for operation, the switch operating portion may beconstructed as follows. That is, it is preferable that when the switchoperating portion is pushed and moved by the door, the switch operatingportion is rotated and moved in the lateral direction that intersectswith an operation direction of the operation button substantially atright angles so that the switch operating portion is moved to thenon-limited region. In this case, even if the operation button that mustbe operated downward strongly at the time of operation is disposed onthe switch operating portion, no problem is caused. This is because evenif the switch operating portion is pushed down unnecessarily stronglyduring normal operation, the switch operating portion is not prone tomove into the non-limited region. Thus the operability of the switchoperating portion is stabilized.

[0029] Of course, in the second steering wheel, the switch operatingportion may previously disposed in the non-limited region of the door.

BRIEF DESCRIPTION OF THE DRAWINGS

[0030]FIG. 1 is a plan view of a steering wheel of a first embodiment ofthe present invention, and is a plan view showing a door of a pad;

[0031]FIG. 2 is a partial plan view of the steering wheel of the firstembodiment, and is a plan view showing a folded state of the bag holderand the airbag;

[0032]FIG. 3 is a schematic sectional view of the steering wheel of thefirst embodiment taken along a line III-III in FIG. 1;

[0033]FIG. 4 is a schematic sectional view of the steering wheel of thefirst embodiment taken along a line IV-IV in FIG. 1;

[0034]FIG. 5 is a schematic enlarged sectional view showing a hinge of afront door of a pad of the first embodiment;

[0035]FIG. 6 is a schematic enlarged sectional view showing the hinge ofthe left door of the pad of the first embodiment;

[0036]FIG. 7 is a bottom view of the pad of the first embodiment;

[0037]FIG. 8 is a plan view of a bag holder used for an airbag apparatusof the first embodiment;

[0038]FIG. 9 is a plan view of a support plate used for the airbagapparatus of the first embodiment;

[0039]FIG. 10A is a plan view showing a state in which the airbag of thefirst embodiment is developed flatly, and

[0040]FIG. 10B is a sectional view taken along a line X-X in FIG. 10A;

[0041]FIGS. 11A, 11B and 11C are views for explaining folding step ofthe airbag apparatus of the first embodiment;

[0042]FIG. 12 is a sectional view taken along a line XII-XII in FIG.11B;

[0043]FIG. 13 is a sectional view taken along a line XIII-XIII in FIG.11C;

[0044]FIG. 14 shows a modification of the first embodiment, and is aplan view of the steering wheel in which a switch operating portion isdisposed on another position;

[0045]FIG. 15 shows another modification of the first embodiment, andshows a holding structure of the pad of the bag holder in themodification;

[0046]FIG. 16 shows another modification of the first embodiment, andshows a holding structure of the pad of the bag holder in themodification;

[0047]FIG. 17 shows another modification of the first embodiment, andshows a holding structure of the pad of the bag holder in themodification;

[0048]FIG. 18 is a plan view of a steering wheel of a second embodiment,and is a plan view showing a door of a pad;

[0049]FIG. 19 is a partial plan view of the steering wheel of the secondembodiment, and is a plan view showing a folded state of the airbag;

[0050]FIG. 20 is a schematic sectional view of the steering wheel of thesecond embodiment taken along a line XX-XX in FIG. 18;

[0051]FIG. 21 is a plan view of a support plate used for the airbagapparatus of the second embodiment;

[0052]FIG. 22 is a plan view showing the supporting state of the switchoperating portion of the second embodiment;

[0053]FIG. 23 is a schematic sectional view of the steering wheel whenthe airbag is developed and expanded in the second embodiment;

[0054]FIG. 24 is a schematic sectional view of a steering wheel of athird embodiment;

[0055]FIGS. 25A and 25B are plan views showing the supporting state ofthe switch operating portion of the third embodiment;

[0056]FIG. 26 is a schematic sectional view of the steering wheel whenthe airbag is developed and expanded;

[0057]FIG. 27 is a schematic sectional view of a steering wheel of afourth embodiment;

[0058]FIGS. 28A and 28B are partial sectional views showing a supportingstate of a switch operating portion of the fourth embodiment;

[0059]FIG. 29 is a schematic sectional view of the steering wheel whenthe airbag of the fourth embodiment is developed and expanded;

[0060]FIG. 30 is a schematic sectional view of a steering wheel of afifth embodiment;

[0061]FIG. 31 is a plan view showing a supporting state of a switchoperating portion of the fifth embodiment;

[0062]FIG. 32 is a schematic sectional view of the steering wheel whenthe airbag of the fifth embodiment is developed and expanded; and

[0063]FIG. 33 is a schematic sectional view of a steering wheel of asixth embodiment.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0064] The invention will be described below by way of embodiments shownin the drawings. In addition, the invention is not limited to theembodiments. All modifications within the requirements of the claims andequivalents will respect to the requirements should be included in thescope of the claims.

[0065] As shown in FIGS. 1 to 4, a steering wheel W1 of a firstembodiment is of three spokes type, and comprises a ring R, a boss B andthree spokes S (SL, SR, and SB). The ring R is annular in shape and isgrasped at the time of steering operation. The boss B is disposed at acenter of the ring R. Each of the spokes S connects the ring R and theboss B with each other. The steering wheel W1 comprises, as constituentparts, a steering wheel body 1, an airbag apparatus 10, and a switchoperating portion 66. The airbag apparatus 10 is disposed on an upperportion of the boss B.

[0066] The steering wheel body 1 includes a steering wheel core 2 and alower cover 8. The steering wheel core 2 is disposed such as to connecteach part of the ring R, the boss B and the spokes S. The lower cover 8is disposed such as to cover a lower portion of the boss B.

[0067] The steering wheel core 2 comprises a ring core 3, a boss core 4and three spoke cores 5. The ring core 3 is disposed on the ring R andits cross section is of reversed U-shape. The boss core 4 is connectedto a steering shaft 80 (see FIG. 3). Each of the spoke cores 5 connectsthe boss core 4 and the ring core 3 with each other. The ring core 3 andthe spoke cores 5 on the side of the ring core 3 are covered withsynthetic resin covering layer 7.

[0068] The boss core 4 comprises a steel boss 4 a and a covering portion4 b made of aluminum alloy, magnesium alloy or the like. The boss 4 a isconnected to the steering shaft 80 with each other. The covering portion4 b covers circumference of the boss 4 a cylindrically. The coveringportion 4 b is integrally die cast together with the ring core 3 and thespoke cores 5.

[0069] Each of the spoke cores 5 extends from the covering portion 4 bof the boss core 4 toward diagonally upward ring core 3. A rear core 5 aof the spoke core 5 extends rearward from the covering portion 4 b, andconnected to the ring core 3. The rear core 5 a is bifurcated on theside of the covering portion 4 b and the bifurcated portions areconverged to the side of the ring core 3 as a single piece. Two branches5 b at a the bifurcated location is formed with mounting seats 5 c. Eachof the mounting seats 5 c includes a mounting hole 5 d for mounting theairbag apparatus 10.

[0070] As shown in FIGS. 3 and 4, the airbag apparatus 10 includes anairbag 11, an inflator 13, a pad 14, a bag holder 50, a horn switchmechanism 57 and a support plate 59. The airbag 11 is folded such thatit can be expanded. The inflator 13 supplies expansion gas to the airbag11. The pad 14 covers the folded airbag 11. The bag holder 50 holds theairbag 11, the inflator 13 and the pad 14. The support plate 59 connectsthe airbag apparatus 10 to the steering wheel body 1 and supports theairbag apparatus 10.

[0071] As shown in FIGS. 2 to 4, 10A and 10B, the airbag 11 has anopening 11 a through which the expansion gas flows. A cross section ofthe airbag 11 at the time of expansion is of substantially ellipsespherical shape. In the case of this embodiment, as shown in FIGS. 10Aand 10B, the airbag 11 is a flat airbag using two cloths D1 and D2. Thatis, the airbag 11 is formed by flatting and superposing the cloths D1and D2 on each other and by connecting the outer peripheries of thecloths D1 and D2 with each other by sewing or the like. Each of thecloths D1 and D2 is formed by cutting a weave such as polyamide string,polyester string or the like into a circular shape. The opening 11 a isformed at its periphery with a plurality of mounting holes 11 b. A bolt12 a of a retainer 12 is inserted through each of the mounting holes 11b. The retainer 12 is for holding the airbag 11 on the bag holder 50,and is substantially annular in shape. Bent holes 11 c and 11 c areformed at portions of the airbag 11 away from the opening 11 a.

[0072] The inflator 13 includes a body 13 a and a flange 13 c. The body13 a is substantially columnar in shape, and is provided at its upperportion with a gas discharge port 13 b. The flange 13 c projects from anouter peripheral surface of the body 13 a.

[0073] The pad 14 is made of synthetic resin such as polyolefin, orpolyethylene thermoplastic elastomer, and is formed by injection formingor the like. As shown in FIGS. 1 to 7, the pad 14 includes a ceilingwall 15 and a side wall 40. The ceiling wall 15 ruptures a predeterminedportion when the airbag 11 expands. The side wall 40 is substantiallyhexagonal cylindrical shape, and extends downward from an outerperiphery of the ceiling wall 15.

[0074] The side wall 40 includes a general portion 41, holding walls 46,47 and 48. The general portion 41 extends downward directly from a lowersurface of the ceiling wall 15. As shown in FIG. 7, the general portion41 comprises a left general portion 41L and a right general portion 41Rand a rear general portion 41B (FIG. 7 is a bottom view of the pad 14,and left and right sides are reversed).

[0075] The left general portion 41L extends from a left front edge ofthe ceiling wall 15 toward a center of the left edge. The left generalportion 41L is provided at its front end and rear end with connectingportions 41Lb and 41Lc, respectively. The front end connecting portion41Lb is connected to a front lateral plate 42. The rear end connectingportion 41Lc is connected to a left lateral plate 43. A portion betweenthe connecting portions 41Lb and 41Lc is a body portion 41La. The bodyportion 41La is exposed toward lower side of the pad 14. The rightgeneral portion 41R is disposed such as to extend from the right frontedge of the ceiling wall 15 toward a center portion of the right edge.The right general portion 41R is provided at its front end and rear endwith connecting portions 41Rb and 41Rc. The front end connecting portion41Rb is connected to a front lateral plate 42. The rear end connectingportion 41Rc is connected to a right lateral plate 44. A portion betweenthe connecting portions 41Rb and 41Rc is a body portion 41Ra, the bodyportion 41Ra exposed at a lower portion of the pad 14. The rear generalportion 41B is disposed such as to extend laterally at a rear edge ofthe ceiling wall 15. The rear general portion 41B is provided at itsleft and right opposite ends with connecting portions 41Bb and 41Bb. Theconnecting portions 41Bb and 41Bb are respectively connected to left andright lateral plates 43 and 44. A portion between the connectingportions 41Bb and 41Bb is a body portion 41Ba, and the body portion 41Bais exposed to a lower portion of the pad 14.

[0076] The front lateral plate 42 extends inwardly and laterally from alower end 21 a of a later-described front outer periphery 21 of theceiling wall 15. The front lateral plate 42 is disposed such as toconnect lower ends of the connecting portions 41Lb and 41Rb of the leftgeneral portion 41L and the right general portion 41R with each other.The left lateral plate 43 extends inwardly and laterally from a lowerend 22 a of a later-described left outer periphery 22 of the ceilingwall 15. The left lateral plate 43 is disposed such as to connect lowerends of the connecting portions 41Lc and 41Bb of the left generalportion 41L and the rear general portion 41B with each other. The rightlateral plate 44 extends inwardly and laterally from a lower end 23 a ofa later-described right outer periphery 23 of the ceiling wall 15. Theright lateral plate 44 is disposed such as to connect lower ends of theconnecting portion 41Rc and 41Bb of the right general portion 41R andthe rear general portion 41B with each other.

[0077] A front holding wall 46 extends downwardly from a rear edge ofthe front lateral plate 42. A left holding wall 47 extends downwardlyfrom an inner edge of a left lateral plate 43. A right holding wall 48extends downward from an inner edge of the right lateral plate 44. Thesefront, left and right holding walls 46, 47 and 48 are respectivelydisposed near hinges 29, 30 and 31 of doors 25, 26 and 27. These front,left and right holding walls 46, 47 and 48 are portions held by bagholder 50. The front, left and right holding walls 46, 47 and 48respectively includes mounting holes 46 b, 47 b, and 48 b and retainingportions 46 a, 47 a, and 48 a. The mounting holes 46 b, 47 b, and 48 bpass through horizontally and provided with steps. A rivet 54 passesthrough the mounting holes 46 b, 47 b, and 48 b. The rivet 54 fixes thefront, left and right holding walls 46, 47, and 48 to a later-describedside wall 52. The retaining portions 46 a, 47 a, 48 a are of projectingand are disposed on upper ends of the front, left and right holdingwalls 46, 47, and 48. Later-described retaining pawls 52 a of the bagholder 50 are retained to the retaining portions 46 a, 47 a, 48 a.

[0078] The ceiling wall 15 is disposed such as to cover an upper portionof the boss B between the covering layers 7 of the spokes SL, SR, andSB. Portions 21, 22, and 23 (front outer periphery 21, left outerperiphery 22 and right outer periphery 23) adjacent to spaces AF, AL,and AR between the spokes SL, SR, and SB are disposed on an outerperiphery of an upper surface of the ceiling wall 15. These front outerperiphery 21, left outer periphery 22 and right outer periphery 23 aredownwardly curved. An opening forming portion 19 is formed in a portionof the ceiling wall 15 which portion is surrounded by the generalportions 41L, 41R, and 41B of the side wall 40. The opening formingportion 19 forms one opening through which the airbag 11 at the time ofexpansion can project. Three spoke side extending portions 16 (16L, 16R,and 16B) are formed around the opening forming portion 19. The spokeside extending portions 16L, 16R, and 16B are disposed such as tosmoothly connect the covering layers 7 of the spokes SL, SR, and SB. Asubstantially cylindrical pushing portion 17 is disposed on lowersurfaces of the spoke side extending portions 16L, 16R, and 16B. Thepushing portion 17 abuts against a mounting piece 53 of the bag holder50 that is positioned upwardly of the horn switch mechanism 57 so as topush the mounting piece 53. Three doors, i.e., a front door 25, a leftdoor 26 and a right door 27 are disposed in the opening forming portion19. A thin to-be ruptured portion 33 that can be ruptured is disposedaround these doors 25, 26 and 27.

[0079] The to-be ruptured portion 33 is disposed at a position adjacentto the doors 25, 26 and 27, and is of substantially T-shape as viewedfrom above. That is, the to-be ruptured portion 33 has a lateral lineportion 34 and a longitudinal line portion 35. The lateral line portion34 is disposed laterally. That is, the lateral line portion 34 isdisposed in the right-left direction. The longitudinal line portion 35extends rearward from substantially center of the lateral line portion34. The lateral line portion 34 is disposed such as to laterally crosssubstantially central portion of the pad 14 in the longitudinaldirection. A central portion of the lateral line portion 34 in theright-left direction is recess rearward as viewed from above such as tobypass a decorative portion 15 a. The decorative portion 15 a is ellipsein shape as viewed from above, and is disposed at a center of theceiling wall 15. Portions of the lateral line portion 34 closer to leftand right opposite ends 34 a and 34 b are disposed toward the left andright spokes SL, SR. The left and right spokes SL, SR extend in theright-left direction in the front side of the steering wheel W1. Aportion of the longitudinal line portion 35 closer to its rear end 35 ais disposed toward the disposition direction of the rear spoke SB. Theto-be ruptured portion 33 includes left and right extending portions 36,37 and a rear extending portion 38. The left and right extendingportions 36 and 37 extend in opposite sides in the longitudinaldirection (the front-rear direction) from left and right opposite ends34 a, 34 b of the lateral line portion 34. The rear extending portion 38extends in opposite sides in the lateral direction from the rear end 35a of the longitudinal line portion 35.

[0080] The left and right extending portions 36, 37 are disposed insidethe left and right general portions 41L, 41R of the side wall 40. Theleft and right extending portions 36, 37 are disposed substantiallyalong the general portions 41L, 41R such as to be in contact with thegeneral portions 41L, 41R. A front end 36 a of the left extendingportion 36 extends toward a lower end 21 a of the front outer periphery21 of the ceiling wall 15 such as be hidden on the left edge side of thefront lateral plate 42 as viewed from below of the pad 14. A rear end 36b of the left extending portion 36 extends toward a lower end 22 a ofthe left outer periphery 22 of the ceiling wall 15 such as to be hiddenby a front edge of the left lateral plate 43 as viewed from below of thepad 14. Similarly, a front end 37 a of the right extending portion 37extends toward a lower end 21 a of a front outer periphery 21 of theceiling wall 15 such as to be hidden by a right edge of the frontlateral plate 42 as viewed from below of the pad 14. Further, a rear end37 b of the right extending portion 37 extends toward a lower end 23 aof the right outer periphery 23 of the ceiling wall 15 such as to behidden by a front edge of the right lateral plate 44 as viewed frombelow of the pad 14.

[0081] The rear extending portion 38 is disposed inside the rear generalportion 41B of the side wall 40. The rear extending portion 38 isdisposed along the general portion 41B such as to be in contact with thegeneral portion 41B. A left end 38 a of the rear extending portion 38extends toward a lower end 22 a of the left outer periphery 22 of theceiling wall 15 such as to be hidden by the rear edge of the leftlateral plate 43 as viewed from below of the pad 14. A right end 38 b ofthe rear extending portion 38 extends toward the lower end 23 a of theright outer periphery 23 of the ceiling wall 15 such as to be hidden bythe rear edge of the right lateral plate 44 as viewed from below of thepad 14.

[0082] In the front door 25, the hinge 29 when the door is opened isdisposed in the vicinity of the space AF. The space AF is a spacebetween the left spoke SL and right spoke SR. The hinge 29 is asubstantially straight portion connecting the front ends 36 a and 37 aof the left and right extending portions 36 and 37. The front door 25 isformed by a portion inside the lateral line portion 34 of the to-beruptured portion 33, and the portions 36F, 37F. The portions 36F, 37Fare portions in front of an intersection of the lateral line portion 34in the left and right extending portions 36 and 37. The front door 25 isaccommodated in the front space AF when the door 25 is opened around thehinge 29 as rotation center.

[0083] The hinge 30 of the left door 26 is disposed in the vicinity ofthe space AL. The space AL is a space between the left spoke SL and therear spoke SB. The hinge 30 is a substantially straight portionconnecting the rear end 36 b of the left extending portion 36 and theleft end 38 a of the rear extending portion 38. The left door 26 isformed by a portion inside of the hinge 30, the portion 34L, thelongitudinal line portion 35, the portion 36B and the portion 38L. Theportion 34L is a portion on the left side of the intersection betweenthe portion 34 and the longitudinal line portion 35 in the lateral lineportion 34 of the to-be ruptured portion 33. The portion 36B is aportion behind the intersection of the portion 36 and the lateral lineportion 34 of the left extending portion 36. The portion 38L is aportion on the left side of the intersection of the portion 38 and thelongitudinal line portion 35 of the rear extending portion 38. When theleft door 26 is opened around the hinge 30 as a rotation center, theleft door 26 is accommodated in the left space AL.

[0084] The right door 27 is laterally symmetric to the left door 26. Thehinge 31 when the right door 27 is opened is disposed in the vicinity ofthe space AR. The space AR is a space portion between the right spoke SRand the rear spoke SB. The hinge 31 is a substantially straight portionconnecting the rear end 37 b of the right extending portion 37 and theright end 38 b of the rear extending portion 38. The right door 27 isformed by a portion inside the hinge 31, the portion 34R, thelongitudinal line portion 35, the portions 37B and 38R. The portion 34Ris a portion on the right side of the intersection between the portion34 and the longitudinal line portion 35 in the lateral line portion 34of the to-be ruptured portion 33. The portion 37B is a portion behindthe intersection between the portion 37 and the lateral line portion 34of the right extending portion 37. The portion 38R is a portion on theright side of the intersection between the portion 38 and thelongitudinal line portion 35 of the rear extending portion 38. When theright door 27 is opened around the hinge 31 as a rotation center, theright door 27 is accommodated in the right space AR.

[0085] The bag holder 50 is die cast made of magnesium or the like forreducing weight and keeping shape. As shown in FIGS. 2 to 6 and 8, thebag holder 50 includes a lateral plate 51 and a side wall 52. Thelateral plate 51 includes an insertion hole 51 a through which theinflator body 13 a can be centrally inserted from below. The side wall52 extends vertically from substantially entire circumference of theouter periphery of the lateral plate 51. A periphery of a the insertionhole 51 a of the lateral plate 51 is formed with a through hole 51 bthrough which the bolt 12 a of the retainer 12 is inserted. The retainer12 has a function for holding the airbag 11 to the bag holder 50 and forholding the inflator 13 to the bag holder 50.

[0086] The side wall 52 abuts against an inner surfaces of the front,left and right holding walls 46, 47 and 48. The side wall 52 is providedwith a plurality of (three, in the embodiment) retaining pawls 52 a atthe top ends of portions thereof which portions abuts against the innersurface of the front, left and right holding walls 46, 47 and 48. Theretaining pawls 52 a are retained to retaining portions 46 a, 47 a, 48 aof the front, left and right holding walls 46, 47 and 48 from above.Each of the retaining pawls 52 a in the side wall 52 is formed at itslower portion with a mounting hole 52 b (see FIGS. 5, 6 and 8). Themounting holes 52 are disposed at positions corresponding to themounting holes 46 b, 47 b, 48 b of the front, left and right holdingwalls 46, 47 and 48. The rivet 54 passes through each mounting hole 52b. The rivets 54 mount the retaining portions 46 a, 47 a, 48 a to theside wall 52.

[0087] Three mounting pieces 53 are formed at upper ends portions nearthe spokes SL, SR and SB in the side wall 52 such as to extend outwardlyin the horizontal direction. A horn switch mechanism 57 is disposedbetween the mounting pieces 53 and a mounting piece 62 of the supportplate 59. The mounting piece 62 is disposed below the mounting pieces53. A nut 53 b is embedded in each of the mounting pieces 53. The nut 53b includes a screw hole 53 a. A stepped bolt 57 d of the horn switchmechanism 57 is threadedly engaged with the screw hole 53 a.

[0088] A lead wire (not shown) is connected to the bag holder 50 such asto bring the bag holder 50 into conduction with a positive pole of ahorn operating circuit.

[0089] The annular retainer 12 is used for holding the airbag 11 and theinflator 13 by the bag holder 50. The retainer 12 is disposed in theairbag 11. The retainer 12 includes a plurality of bolts 12 a. Thesebolts 12 a pass through the through hole 51 b of the bag holder 50 andthe flange 13 c of the inflator 13, and nuts 12 b are threadedly engagedwith the bolts 12 a so that the airbag 11 and the inflator 13 are heldby the bag holder 50. The rivet 54 and the retaining pawls 52 a are usedfor holding the pad 14 by the bag holder 50. That is, the rivets 54mount the front, left and right holding walls 46, 47 and 48 of the padside wall 40 to the side wall 52, and the retaining pawls 52 a retainthe retaining portions 46 a, 47 a, 48 a of the front, left and rightholding walls 46, 47 and 48, so that the pad 14 is held by the bagholder 50.

[0090] As shown in FIGS. 3 and 4, three horn switch mechanisms 57 aredisposed on a back surfaces of the spoke side extending portions 16L,16R, 16B in the pad 14. The spoke side extending portions 16L, 16R, 16Bare disposed near the spokes SL, SR, SB. Each of the horn switchmechanisms 57 is disposed between each mounting piece 53 of the bagholder 50 and each mounting piece 62 of the support plate 59. Each hornswitch mechanism 57 brings contacts 57 a and 57 b by pushing the pad 14down, thereby operates a horn. Each horn switch mechanism 57 separatesthe contacts 57 a and 57 b from each other by a coil spring 57 c whenthe horn is not operated. Further, the horn switch mechanism 57 keeps aseparating distance between the contacts 57 a and 57 b constantly bymeans of the stepped bolt 57 d. The stepped bolt 57 d is threadedlyengaged from below of the mounting piece 62 of the support plate 59 withthe screw hole 53 a of the mounting piece 53 in the bag holder 50.

[0091] As shown in FIGS. 3, 4 and 9, the support plate 59 is made ofplate metal, and includes a connecting rod 60, three vertical plates 61,three mounting pieces 62 and two connecting pieces 64. The connectingrod 60 is of U-shape as viewed from above. Each of the vertical plates61 extends upwardly from a position near the mounting piece 53 of thebag holder 50 in the connecting rod 60. The mounting pieces 62 extendoutwardly in the horizontal direction from upper ends of the verticalplates 61, and are disposed below the mounting pieces 53. The connectingpieces 64 extend downwardly from inner edges of left and right sides ofthe connecting rod 60.

[0092] Each of the mounting pieces 62 is formed at its central portionwith a mounting hole 62 a. An opening shape of the mounting hole 62 a isa combination of a circle hole and substantially right triangular holedisposed at a symmetric position of the circle hole. A stepped bolt 57 dof the horn switch mechanism 57 is inserted through the mounting hole 62a. An outer edge of each mounting piece 62 is formed with an abuttingpiece 63. The abutting piece 63 abuts against the covering layer 7 ofthe spokes SL, SR, and SB and supported.

[0093] A nut 64 b is fixed to each of opposed surfaces of each of theconnecting pieces 64. A bolt 9 is threadedly engaged with the nut 64 b.The bolt 9 mounts the airbag apparatus 10 to each mounting seat 5 c ofthe spoke core 5.

[0094] As shown in FIGS. 1 and 2, the switch operating portion 66 isdisposed such as not to be covered by the doors 25, 26, and 27 when itis opened. In the case of this embodiment, the switch operating portion66 is disposed on the upper surfaces of the left and right spokes SL, SRnear the left and right spoke side extending portions 16L, 16R of thepad 14. In the case of this embodiment, an operation button 67 for theaudio equipment, a shift up button 68 of a shift change, a shift downbutton 69, an operation button 70 of a telephone and an operation lever71 of a navigation system are disposed as the switch operating portion66. The operation buttons 67 is disposed on the left spoke SL. Otherbuttons 68, 69, and 70 and the lever 71 are disposed on the right spokeSR. In these switch operating portions 66, operation surfaces 67 a, 68a, 69 a, 70 a, and 71 a disposed on the upper surface are disposed inthe vicinity of a ring surface P so that they can be operated easilyfrom above when the steering wheel W1 is steered.

[0095] When the steering wheel W1 of the first embodiment is mounted tothe vehicle, the airbag apparatus 10 is previously assembled.

[0096] The airbag apparatus 10 is assembled in the following manner.First, the retainer 12 is inserted into the airbag 11, and each bolt 12a of the retainer 12 is projected from the mounting hole 11 b. Then, theairbag 11 is folded. The airbag 11 is folded in the following manner.Three folding portions 11 j, 11 k, and 11 m (see FIG. 2) are provided,the folding portions 11 j, 11 k, and 11 m are folded such that they canbe disposed below the doors 25, 26, 27. That is, they are folded suchthat pressing force for opening the doors 25, 26, and 27 can reliably besecured by the folding portions 11 j, 11 k, and 11 m.

[0097] The folding step will be described in detail. As shown in FIG.11A, the cloth D2 on the side of the driver opposed to the opening 11 ais superposed on the cloth D1 on the side of the inflator 13, and theairbag 11 is developed flatly. Then, the cloth is folded in two stages.

[0098] In a first stage, as shown in FIGS. 11A, 11B, and 12, peripheries11 d, 11 e, 11 f are folded such as to approach the opening 11 a. Eachof the peripheries 11 d, 11 e, and 11 f is located in three directionsradially divided equally around the opening 11 a. In the case of thisembodiment, the peripheries 11 d, 11 e, and 11 f are folded on the sideof the cloth D2 opposed to the opening 11 a in a form of a bellows forforming an upward crease CM and downward crease CV. After the cloths arefolded, as shown in FIG. 11B, peripheries 11 g, 11 h, 11 i on the sideof folded end are disposed in three directions around the opening 11 a.

[0099] In a second stage, as shown in FIGS. 11B, 11C, and 13, theperipheries 11 g, 11 h, and 11 i are folded such as to approach theopening 11 a to form the folding portions 11 j, 11 k, and 11 m, therebycompleting the folding operation of the airbag 11. In the case of thisembodiment, the peripheries 11 g, 11 h, and 11 i on the side of thefolded end in the first stage are folded by outer roll folding. That is,the peripheries 11 g, 11 h, and 11 i are wound on the side of the clothD1 having the opening 11 a. The wound portion is placed on the side ofthe cloth D2 opposed to the opening 11 a and folded.

[0100] After the folding operation of the airbag 11 has been completed,in order to prevent the crease from being restored and eliminated, theairbag 11 may be wrapped by a thin wrapping bag that can be ruptured.

[0101] After the airbag 11 is folded, it is accommodated in the bagholder 50. In this step, each bolt 12 a of the retainer 12 projectingfrom the airbag 11 is inserted through the through hole 51 b of the bagholder lateral plate 51, and the airbag 11 is placed on the lateralplate 51 surrounded by the side wall 52 (see FIG. 11C).

[0102] At that time, three clots (folded portions) 11 j, 11 k, and 11 mformed by folding in the second stage are disposed as follows. The clot11 j is disposed on the side of the front edge of the lateral plate 51,the clot 11 k is disposed on the left side on the side of the rear edgeof the lateral plate 51, the clot 11 m is disposed on the right side onthe side of the rear edge of the lateral plate 51, and the airbag 11 isplaced on the lateral plate 51. The bent holes 11 c, 11 c are disposedon the portion of the clot 11 j.

[0103] Then, the body 13 a of the inflator 13 is inserted through theinsertion hole 51 a of the bag holder lateral plate 51, and the bolt 12a of the retainer 12 is inserted through the inflator flange 13 c. Theflange 13 c of the inflator 13 is abutted against a lower surface of thelateral plate 51. The nut 12 b is threadedly engaged with the bolt 12 aprojecting from the flange 13 c, and the airbag 11, the bag holder 50and the inflator 13 are integrally assembled.

[0104] Thereafter, the pad 14 is pushed down from above such as tosurround the outer peripheral surface on the side of the folded airbag11 by the side wall 40. Then, the retaining pawls 52 a of the bag holder50 are retained to the retaining portions 46 a, 47 a, and 48 a of thefront, left and right holding walls 46, 47, and 48. The mounting holes46 b, 47 b, and 48 b of the front, left and right holding walls 46, 47,and 48 are aligned to the mounting holes 52 b of the bag holder 50.Then, the rivets 54 are inserted into the mounting holes 46 b, 47 b, 48b, and the front, left and right holding walls 46, 47, and 48 and theside wall 52 are fastened.

[0105] The horn switch mechanism 57 is disposed on each of the mountingpieces 62 of the support plate 59, and the portions of the horn switchmechanisms 57 are disposed on the lower surface of the mounting pieces53 of the bag holder 50. Next, the stepped bolt 57 d is threadedlyengaged with the screw hole 53 a, thereby assembling the airbagapparatus 10.

[0106] The lower cover 8 is mounted to the steering wheel core 2utilizing a screw or the like, the switch operating portion 66 isdisposed and the steering wheel body 1 is assembled. The steering wheelcore 2 is produced by die casting and then, the covering layer 7 isformed. The boss 4 a of the boss core 4 is fitted around the steeringshaft 80 of the vehicle, the nut 81 is threadedly engaged, and thesteering wheel body 1 is mounted to the steering shaft 80. The steeringshaft 80 is inclined such that its upper end is directed upward throughabout 30° with respect to the horizontal direction along the ground.

[0107] Lead wires (not shown) extending from the horn switch mechanism57 of the airbag apparatus 10 and the various switch operating portions66 are connected to a connector (not shown) on the side of the steeringwheel body 1. Further, each of the abutting pieces 63 of the supportplate 59 of the airbag apparatus 10 is abutted and supported against thecovering layer 7 of the spokes SL, SR, and SB, and the connecting pieces64, 64 are abutted against the inner surface of the mounting seats 5 cof the rear core 5 a. Next, the mounting bolts 9 are threadedly engagedwith the connecting holes 64 a of the connecting pieces 64 from the hole8 a of the lower cover 8 through the mounting holes 5 d of the mountingseats 5 c. As a result, the steering wheel W1 can be assembled and thesteering wheel W1 can be mounted to the steering shaft 80.

[0108] In the steering wheel W assembled in the above-described manner,a predetermined device is operated by pushing down or swinging theoperation surfaces 67 a, 68 a, 69 a, 70 a, and 71 a of the switchoperating portions 66 (operation buttons 67, 70, the shift up button 68,the shift down button 69, and the operation lever 71).

[0109] If the inflator 13 is actuated, the expansion gas from theinflator 13 flows into the airbag 11. Then, the airbag 11 expands andthe folding portions 11 j, 11 k, and 11 m are developed to push up thethree doors 25, 26 and 27 of the pad 14. Therefore, the doors 25, 26,and 27 of the pad 14 rupture the to-be ruptured portion 33 and opensaround the hinges 29, 30, and 31 as rotation centers. As a result, theopening forming portion 19 largely opens, the airbag 11 projects fromthe pad 14 and expands into a predetermined shape.

[0110] When the airbag 11 is developed and expanded, the hinges 29, 30,and 31 of the doors 25, 26, and 27 are located near the spaces AF, AL,and AR between the spokes SL, SR, and SB. The hinges 29, 30, and 31 aredisposed on the side of the lower ends 21 a, 22 a, and 23 a of the padouter peripheries 21, 22, and 23 lower than a portion Z (see FIGS. 3, 5,and 6). The portion Z is above the holding portions (front, left andright holding walls) 46, 47 and 48 by the bag holder 50 near the hinges29, 30, and 31 in the pad 14 (ceiling wall 15). Therefore, the doors 25,26, and 27 open around the hinges 29, 30, 31 located near the outerperiphery lower ends 21 a, 22 a, and 23 a of the pad 14. As a result,the doors 25, 26, and 27 can secure their own areas widely. The doors25, 26, and 27 secure wide opening area and open as wide as possible.

[0111] When the doors 25, 26, and 27 open around the hinges 29, 30, and31, the doors 25, 26, and 27 are disposed in the three spaces AL, AR,and AB between the spokes SL, SR, and SB. The switch operating portions66 are disposed in areas of the spokes SL, SR that are not covered withthe opened doors 25, 26, and 27. Therefore, the opened doors 25, 26, and27 do not interfere with the switch operating portions 66 and disposedsmoothly in the three spaces AF, AL, and AR. As a result, the doors 25,26, and 27 can widely open and their states can be stably secured.

[0112] Therefore, according to the steering wheel W1 of the firstembodiment, even if the switch operating portions 66 are disposed on thespokes SL, SR near the boss B, the doors 25, 26 and 27 of the pad 14 canwidely open. According to the steering wheel W1 of the first embodiment,the airbag 11 at the initial expansion stage can widely develop. As aresult, in a state in which the driver is close to the steering wheel W,even if the airbag 11 is developed and expanded, it is possible toprevent the airbag 11 from applying a partial pushing force to thedriver.

[0113] In the pad 14 of the first embodiment, portions of the to-beruptured portions 33 which are respectively adjacent to the doors 25,26, and 27 are of substantially T-shape as viewed from above, and havethe lateral line portion 34 and the longitudinal line portion 35. Thelateral line portion 34 is disposed laterally. The longitudinal lineportion 35 extends rearward from substantially central portion of thelateral line portion 34. Left and right opposite ends 34 a, 34 b of thelateral line portion 34 are directed to the front left and right spokesSL, SR. In the steering wheel W1 of the first embodiment of three spokestype, among the spaces AF, AL, and AR between the spokes SL, SR, and SB,the front space AF is set greater than rear left and right spaces AL, ARso that the measuring instruments of the instrument panel can easily beseen. Therefore, if the to-be ruptured portions 33 adjacent to the doors25, 26 and 27 are substantially T in shape, the front door 25 in frontof the lateral line portion 34 of the to-be ruptured portion 33 has agreater area. The left and right doors 26, 27 divided by the rearlongitudinal line portion 35 that is behind the lateral line portion 34have smaller area. As a result, shapes of the front, left and rightdoors 25, 26, and 27 can easily be fit to the front, left and rightspaces AF, AL, and AR in which the doors are accommodated when theyopened. That is, the shapes of the front, left and right doors 25, 26,and 27 can easily be set.

[0114] The pad 14 of the first embodiment has the ceiling wall 15 andthe side wall 40. The ceiling wall 15 has the doors 25, 26 and 27 andthe to-be ruptured portion 33 and is disposed on the side of the upperportion of the pad 14. The side wall 40 extends downward from theceiling wall 15 and is disposed in the vertical direction such that theside wall 40 can be connected to the bag holder 50. Remaining portions36, 37, and 38 of the to-be ruptured portion 33 except the adjacentportions 34, 35 which adjoin the doors 25, 26, and 27 approach the innersurfaces of the general portions 41L, 41R, and 41B of the side wall 40in the ceiling wall 15 and are disposed substantially along the sidewall general portions 41L, 41R, and 41B. The general portions 41L, 41R,and 41B of the side wall 40 are portions which increase the thickness ofthe ceiling wall 15. That is, the remaining portions 36, 37, and 38 ofthe to-be ruptured portion 33 approach the inner surface of the portion41 which increases the thickness of the ceiling wall 15. Therefore,stress concentration is prone to be generated in the remaining portions36, 37, and 38. Further, the remaining portions 36, 37, and 38 aredisposed along the general portion 41 of the side wall 40. Therefore,the remaining portions 36, 37, and 38 rupture easily along the generalportion 41. As a result, the to-be ruptured portion 33 easily rupturesand the doors 25, 26, and 27 smoothly open.

[0115] In the first embodiment, the switch operating portions 66 aredisposed on the portions of the spokes SL, SR on the side of thesteering wheel body 1 not on the side of the pad 14. However, as shownin FIG. 14, the switch operating portions 66 may be disposed in an areawhich other than the portions of the doors 25, 26, and 27 and which arenot covered by the opened doors 25, 26, and 27. That is, the switchoperating portions 66 may be disposed on the portions 16L, 16R of thepad 14 or the spoke side extending portions 16B. Of course, the switchoperating portions 66 may be disposed both the spokes S side and the pad14 side only if they are not covered with the opened doors 25, 26, and27. The switch operating portion may be disposed such as to project notonly from the pad 14 but also from the lower cover 8, or from the boss Bof the steering wheel body 1 toward the spaces AL, AR.

[0116] In the first embodiment, the pad 14 is held by the bag holder 50by retaining the retaining pawls 52 a to the retaining portions 46 a, 47a, and 48 a and by using the rivet 54. However, if the hinges 29, 30,and 31 of the doors 25, 26, and 27 are disposed near the spaces AF, AL,and AB between the spokes, and if the hinges 29, 30, and 31 are disposedon the side of the outer peripheries 21, 22, and 23 of the pad 14 whichis lower than the portion Z located above the holding portions 46, 47,and 48 held by the bag holder 50 in the vicinity of the hinges 29, 30,and 31, the pad 14 may be held on the bag holder 50 only by the rivet54. Alternatively, the pad 14 may be held as shown in FIGS. 15, 16, and17.

[0117] According to the holding structure shown in FIG. 15, a bag holder50A holds the holding walls 46, 47, and 48 utilizing a metal auxiliaryplate 55. The side wall 52 of the bag holder 50A is formed with aretaining pawl 52 a. The retaining pawl 52 a retains projectingretaining portions 46 a, 47 a, and 48 a of the holding walls 46, 47, and48. On the other hand, the auxiliary plate 55 is formed with aninsertion piece 55 a. Lower end surface of the holding walls 46, 47, and48 are formed with insertion grooves 46 c, 47 c, and 48 c through whichthe insertion piece 55 a is inserted. The holding walls 46, 47, and 48are sandwiched between the retaining pawls 52 a of the bag holder 50Aand the insertion piece 55 a of the auxiliary plate 55, and held by thebag holder 50A. The auxiliary plate 55 is fastened to the lateral plate51 of the bag holder 50A utilizing the bolt 12 a and nut 12 b of theretainer 12.

[0118] According to the holding structure shown in FIG. 16, a bag holder50B holds the holding walls 46, 47, and 48 utilizing a metal auxiliaryplate 56. The side wall 52 of the bag holder 50B is formed with aretaining pawls 52 c retained to a peripheries of the retaining portions(holes) 46 d, 47 d, and 48 d provided on the holding walls 46, 47, and48. The auxiliary plate 56 is formed with a restriction wall 56 a thatabuts against an outer surfaces of the holding walls 46, 47, and 48.That is, the retaining pawls 52 c are prevented from being out from theretaining portions 46 d, 47 d, and 48 d by the restriction wall 56 a.The holding walls 46, 47, and 48 are retained by the retaining pawls 52c which are prevented from being out and held by the bag holder SOB. Theauxiliary plate 56 is also fastened to the lateral plate 51 of the bagholder 50B utilizing the bolt 12 a and nut 12 b of the retainer 12.

[0119] According to the holding structures shown in FIGS. 15 and 16, thehinges 29, 30, and 31 of the doors 25, 26 and 27 are located near thespaces AF, AL, AR between the spokes, and are disposed on the side ofthe lower ends 21 a, 22 a, and 23 a of the outer peripheries 21, 22, and23 of the pad 14 that is lower than the portion Z above the holdingwalls 46, 47, and 48 by the bag holder 50 near the hinges 29, 30, and31. Therefore, the doors 25, 26, and 27 shown in FIGS. 15, 16 can widelyopen.

[0120] According to the holding structure shown in FIG. 17, the bagholder 50C and the pad 14 do not have the side walls 52, 40. The lateralplate 42, 43, and 44 of the pad are retained on portions of the lateralplate 51 of the bag holder 50C using the rivets 45, the pad 14 is heldon the bag holder 50C. With this holding structure also, the hinges 29,30, and 31 of the doors 25, 26, and 27 are located near the spaces AF,AL, and AR between the spokes, and are disposed on the side of the lowerends 21 a, 22 a, and 23 a of the outer peripheries 21, 22, and 23 of thepad 14 that is lower than the portion Z above the holding positions(disposed position of the rivet 45) by the bag holder 50 near the hinges29, 30, and 31. Therefore, the doors 25, 26, and 27 shown in FIG. 17 canalso widely open also.

[0121] A steering wheel W2 of a second embodiment, as shown in FIGS. 18to 20, has a ring R, a boss B and three spokes S (SL, SR, and SB) likethe first embodiment. The steering wheel W2 comprises, as constituentparts, a steering wheel body 1, an airbag apparatus 10 and a switchoperating portion 167.

[0122] In the steering wheel W2 of the second embodiment, only thesupport plate 59A and the switch operating portion 167A are differentfrom those of the first embodiment, and other members are the same asthose of the first embodiment. Therefore, the members in the secondembodiment which are the same as those of the first members aredesignated with the same symbols, and explanation thereof is omitted.

[0123] In the steering wheel W2 of the second embodiment, when the door26 of the pad 14 opened, the switch operating portion 167 is disposed inan area below the door 26.

[0124] As shown in FIG. 21, a support plate 59A of the second embodimentis made of plate metal, and includes a connecting rod 60, three verticalplates 61, three mounting pieces 62, two connecting pieces 64 and asupport piece 65. The second embodiment is different from the firstembodiment in that the support plate 59A includes the support piece 65.That is, the connecting rod 60 is of U-shape as viewed from above likethe support plate 59 in the first embodiment, each of the verticalplates 61 extends upwardly from a position of the bag holder 50 in theconnecting rod 60 near the mounting piece 53 like the support plate 59of the first embodiment (see FIGS. 3 and 20). Like the support plate 59of the first embodiment, each of the mounting pieces 62 extendsoutwardly in the horizontal direction from an upper end of each of thevertical plates 61 and disposed below the mounting piece 53. Each of theconnecting pieces 64 extends downwardly from inner edges of left andright opposite sides of the connecting rod 60. The support piece 65extends outwardly from outer edges of left side of the connecting rod60.

[0125] Each of the mounting pieces 62 is formed at its center with amounting hole 62 a. A stepped bolt 57 d of the horn switch mechanism 57is inserted into the mounting hole 62 a. The mounting piece 62 is formedat its outer edge with an abutment piece 63. The abutting piece 63 abutsagainst and supported by the covering layers 7 of the spokes SL, SR, andSB. A nut 64 b having a connection hole 64 a is fixed to the connectingpieces 64 on the side of the opposed surface. A bolt 9 is threadedlyengaged with the connection hole 64 a, and the bolts 9 mount the airbagapparatus 10 to the mounting seats 5 c of the spoke core 5 (see FIG. 4).

[0126] As shown in FIGS. 20, 21, 22, the support piece 65 hassubstantially L-shaped cross section, and includes an extending portion65 a and a support portion 65 c. The extending portion 65 a extendsoutwardly in the lateral direction from the connecting rod 60. Thesupport portion 65 c extends upwardly from the vicinity of a tip end ofthe extending portion 65 a. The support portion 65 c is formed with aplurality (two in the embodiment)of mounting hole 65 d. A screw 170 formounting and fixing the switch operating portion 167 is inserted intothe mounting hole 65 d. A to-be deformed portion 65 b is formed on anintersection between the extending portion 65 a and the support portion65 c. The to-be deformed portion 65 b is a portion for inclining thesupport portion 65 c such as to rotate the same outwardly around theintersection. The to-be deformed portion 65 b has a reversed U-shapedcross section and is curved so that it can easily be deformedplastically.

[0127] As shown in FIGS. 18 to 20 and 22, the switch operating portion167 is supported by the support portion 65 c of the support piece 65,and is disposed such as to project toward the left space AL. The switchoperating portion 167 is disposed below the opened left door 26. Theswitch operating portion 167 includes a case 168 and a plurality ofoperation buttons 169. Screws 170, 170 are threadedly engaged with thecase 168 through the mounting hole 65 d of the support portion 65 c, andthe switch operating portion 167 is mounted to the support portion 65 c.The plurality of operation buttons 169 project upwardly from the case168. In the case of this embodiment, the operation buttons 169 operatethe audio equipment. Each of the operation buttons 169 is provided atits upper surface with an operating surface 169 a. Each the operatingsurface 169 a is close to the ring surface P so that the operationbuttons 169 can easily be operated from above when the steering wheel W2is steered. If the operating surface 169 a is pushed down, the operationbuttons 169 is operated.

[0128] In the case of this embodiment, when the switch operating portion167 is supported by the support portion 65 c of the support piece 65using the screws 170, the upper portion 167 a is disposed near the outerside of the hinge 30 of the door 26 and above the hinge 30.

[0129] When the steering wheel W2 of the second embodiment is mounted tothe vehicle, the airbag apparatus 10 is previously assembled like thefirst embodiment.

[0130] Like the first embodiment, the airbag apparatus 10 is assembledby inserting the retainer 12 into the airbag 11, by projecting the bolts12 a of the retainer 12 from the mounting holes 11 b and then, byfolding the airbag 11. The airbag 11 is folded in such a manner thatthree folded portions 11 j, 11 k, and 11 m (see FIG. 19) are prepared,the folded portions 11 j, and 11 k, 11 m are disposed below the doors25, 26 and 27 of the pad 14. That is, when the airbag 11 is developedand expanded, the doors 25, 26, and 27 can reliably receive the pushingforce of the folded portions 11 j, 11 k, and 11 m.

[0131] After the folding operation of the airbag 11 was completed, likethe first embodiment, in order to prevent the crease from being restoredand eliminated, the airbag 11 may be wrapped by a thin wrapping bag thatcan be ruptured.

[0132] After the airbag 11 is folded, it is accommodated in the bagholder 50. In this step, each bolt 12 a of the retainer 12 projectingfrom the airbag 11 is inserted through the through hole 51 b of the bagholder lateral plate 51, and the airbag 11 is placed on the lateralplate 51 surrounded by the side wall 52. At that time, three clots(folded portions) 11 j, 11 k, and 11 m are disposed as follows. The clot11 j is disposed on the side of the front edge of the lateral plate 51,the clots 11 k and 11 m are disposed on the left and right sides on theside of the rear edge of the lateral plate 51, and the airbag 11 isplaced on the lateral plate 51.

[0133] Then, the body 13 a of the inflator 13 is inserted through theinsertion hole 51 a of the bag holder lateral plate 51, and the bolt 12a of the retainer 12 is inserted through the inflator flange 13 c. Theflange 13 c of the inflator 13 is abutted against a lower surface of thelateral plate 51. The nut 12 b is threadedly engaged with the bolt 12 aprojecting from the flange 13 c, and the airbag 11, the bag holder 50and the inflator 13 are integrally assembled.

[0134] Thereafter, the pad 14 is pushed down from above such as tosurround the outer peripheral surface on the side of the folded airbag11 by the side wall 40. Then, the retaining pawls 52 a of the bag holder50 are retained to the retaining portions 46 a, 47 a, and 48 a (seeFIGS. 3 and 7 for the retaining portions 46 a, 48 a) of the front, leftand right holding walls 46, 47, and 48. The mounting holes 46 b, 47 b,and 48 b (see FIGS. 3 and 7 for the mounting holes 46 b, 48 b) of thefront, left and right holding walls 46, 47, and 48 are aligned to themounting holes 52 b of the bag holder 50. Then, the rivets 54 areinserted into the mounting holes 46 b, 47 b, 48 b, and 52 b and thefront, left and right holding walls 46, 47, and 48 and the side wall 52are fastened.

[0135] Then, the switch operating portion 167 is mounted to the supportportion 65 c of the support piece 65 of the support plate 59A using thescrews 170. The horn switch mechanisms 57 are disposed on the mountingpieces 62 of the support plate 59A, and the portions of these hornswitch mechanisms 57 are disposed on the lower surfaces of the mountingpieces 53 of the bag holder 50. Further, the stepped bolt 57 d isthreadedly engaged with the screw hole 53 a from below the mountingpieces 62, and the airbag apparatus 10 can be assembled.

[0136] The lower cover 8 is mounted to the steering wheel core 2 havingthe covering layer 7 using a screw or the like, and the steering wheelbody 1 is assembled. Then, the boss 4 a of the boss core 4 is fittedaround the steering shaft 80 of the vehicle (see FIG. 3) and then, thesteering wheel body 1 is mounted to the steering shaft 80 using the nut81.

[0137] Then, lead wires (not shown) extending from the horn switchmechanism 57 of the airbag apparatus 10 and the various switch operatingportions 167 are connected to a connector (not shown) on the side of thesteering wheel body 1. Further, each of the abutting piece 63 of thesupport plate 59 of the airbag apparatus 10 is abutted and supportedagainst the covering layer 7 of the spokes SL, SR, and SB, and theconnecting pieces 64, 64 are abutted against the inner surface of themounting seats 5 c of the rear core 5 a. Next, the mounting bolts 9 arethreadedly engaged with the connecting holes 64 a of the connectingpieces 64 from the hole 8 a (see FIG. 4) of the lower cover 8 throughthe mounting holes 5 d of the mounting seats 5 c. As a result, thesteering wheel W2 can be assembled and the steering wheel W2 can bemounted to the steering shaft 80.

[0138] In the steering wheel W2 assembled in the above-described manner,the operating surface 169 a of each the operation button 169 of theswitch operating portion 167 is pushed down, the predetermined equipmentis operated.

[0139] If the inflator 13 is actuated, the expansion gas from theinflator 13 flows into the airbag 11. Then, the airbag 11 expands andthe folding portions 11 j, 11 k, 11 m are developed to push up the threedoors 25, 26, and 27 of the pad 14. Therefore, the doors 25, 26 and 27of the pad 14 rupture the to-be ruptured portion 33 and open around thehinges 29, 30, and 31 as rotation centers. As a result, the openingforming portion 19 largely opens, the airbag 11 projects from the pad 14and expands into a predetermined shape.

[0140] When the airbag apparatus 10 is developed and expanded like inthe same manner as the first embodiment, the hinges 29, 30, and 31 ofthe doors 25, 26, and 27 are located near the spaces AF, AL, and ARbetween the spokes SL, SR, and SB, and the hinges 29, 30, and 31 aredisposed on the side of the lower ends 21 a, 22 a, and 23 a of the padouter peripheries 21, 22, and 23 lower than a portion Z (see FIGS. 20,3, and 7). The portion Z is above the holding portions (front, left andright holding walls) 46, 47, and 48 held by the bag holder 50 near thehinges 29, 30, and 31. Therefore, the doors 25, 26 ,and 27 open aroundthe hinges 29, 30, and 31 located near the outer periphery lower ends 21a, 22 a, and 23 a of the pad 14. As a result, the doors 25, 26, and 27can secure their own areas widely and open as wide as possible.

[0141] When the left door 26 opened around the hinge 30 as a rotationcenter, as shown in FIG. 23, the upper portion 167 a of the switchoperating portion 167 is pushed by the door 26 that opens rapidly.Therefore, the to-be deformed portion 65 b is plastically deformed, thesupport portion 65 c of the support piece 65 rotates and moves aroundthe to-be deformed portion 65 b such as to be inclined toward the spaceAL. As a result, the switch operating portion 167 supported by thesupport portion 65 c is disposed in the non-limited region. Thisnon-limited region is a region where the switch operating portion 167does not limit the opening completion state of the door 26. Thus, thedoor 26 completes the opening operation in the widely opened statewithout being limited by the switch operating portion 167.

[0142] Therefore, according to the steering wheel W2 having the airbagapparatus 10 in the second embodiment, even if the switch operatingportion 167 is disposed below the pad opened door 26, the door 26 of thepad 14 can widely open. Thus, the initially expanding airbag 11 canwidely develop. As a result, even if the airbag 11 is developed andexpanded in a state in which the driver is close to the steering wheelW2, it is possible to prevent the airbag 11 from applying a partialpushing force to the driver.

[0143] In the second embodiment, the switch operating portion 167 ispushed by the opening door 26 and rotated and moved, while plasticallydeforming the to-be deformed portion 65 b, and the switch operatingportion 167 is disposed in the non-limited region. In the normal statebefore the door 26 opens, the switch operating portion 167 can bedisposed such as to approach the ring surface P located at upperposition. Thus, in the second embodiment, even if the switch operatingportion 167 is disposed at a lower position below the pad door 26 whichis opened, the door 26 can widely open, and the operability of theswitch operating portion 167 is enhanced.

[0144] If the switch operating portion 167 is designed such that it ispushed by the opening door 26 and moved and disposed in the non-limitedregion, the switch operating portion 167 may be constructed like asteering wheel W3 of a third embodiment shown in FIGS. 24 to 26.

[0145] In the steering wheel W3 of the third embodiment, a mounting hole65 d provided on a support portion 65 c of a support piece 65A is madeas a long hole extending vertically. The screws 170, 170 set thefastening strength to a predetermined value. The screws 170, 170 arethreadedly engaged with a case 168 of a switch operating portion 167.The fastening strength of the screw 170 is set to such a degree that theswitch operating portion 167 is not lowered by a normal pushing downoperation of the operation buttons 169 to the operating surface 169 a(see FIGS. 24 and 25A). The fastening strength of each of the screws170, 170 is set such that when the door 26 abuts against the upperportion 167 a of the switch operating portion 167 from above, the switchoperating portion 167 can be lowered along the long hole mounting hole65 d in a state in which the screw 170 is threaded (see FIGS. 25B and26). A vertical length of the mounting hole 65 d is set to such a degreethat when the switch operating portion 167 is disposed on the upperportion, excellent operability can be secured, and when the door 26opens, the switch operating portion 167 can be disposed in thenon-limited region of the door 26.

[0146] With this steering wheel W3 of the third embodiment, the sameworking effect as that of the second embodiment can be obtained.

[0147] Further, a steering wheel may be constructed as a steering wheelW4 of a fourth embodiment shown in FIGS. 27 to 29. In this steeringwheel W4, a case 168 itself of a switch operating portion 167A is shrunkby pushing force of the door 26. That is, the case 168 includes a lowercase 168 a and an upper case 168 b. The lower case 168 a is disposed ata lower portion of the case 168. The lower case 168 a is mounted to thesupport portion 65 c of the support piece 65B using a screw 170, andsupported by a support portion 65 c. The upper case 168 b is disposedabove the lower case 168 a. The upper case 168 b is formed at its outerperiphery with a projecting position limiting portion 168 c. With anormal operation of the operation buttons 169 for pushing down theoperating surface 169 a, the position limiting portion 168 c limits theposition (see FIGS. 27, 28A), and the upper case 168 b does not movetoward the lower case 168 a. When the door 26 opens, if the door 26abuts against the upper portion 167 a of the switch operating portion167A from above, the position limiting portion 168 c can not limit theposition by this pushing force. That is, the upper case 168 b moves intothe lower case 168 a (see FIGS. 28B, 29), the upper portion 167 a of theswitch operating portion 167A is located in the non-limited region ofthe door 26. With this steering wheel W4 of the fourth embodiment, thesame working effect as those of the first and second embodiments.

[0148] Further, a steering wheel may be constructed as a steering wheelW5. of a fifth embodiment shown in FIGS. 30 to 32. In this steeringwheel W5, a lower end of a switch operating portion 167B is supported onthe support portion 65 c of the support piece 65C so that the lower endcan rotate toward the space AL. A plurality of retaining pawls 16 dextending from the case 168 is disposed on an upper portion of theswitch operating portion 167B. The retaining pawls 168 d retain theedges 65 g, 65 g on the side surfaces of the support portion 65 c.Brackets 65 e, 65 e holding a support shaft 65 f are disposed onopposite sides of a lower end of the support portion 65 c of the supportpiece 65C. The switch operating portion 167B is rotatably supported bythe support shaft 65 f. An upper portion 167 a of the switch operatingportion 167B projects upward from the support portion 65 c. The upperportion 167 a of the switch operating portion 167B is disposed near theouter side of the hinge 30 of the door 26 and above the hinge 30.

[0149] According to the steering wheel W5 of the fifth embodiment, whenthe left door 26 opens around the hinge 30 as rotation center, as shownin FIG. 32, the upper portion 167 a of the switch operating portion 167Bis pushed by the door 26 that opens rapidly. Then, the retaining pawls168 d come out from the supporting both edges 65 g, 65 g, and the switchoperating portion 167B is rotated and moved around the support shaft 65f as the rotation center such as to be inclined toward the space AL. Asa result, the switch operating portion 167B is disposed in thenon-limited region where the opening completion state of the door 26 isnot limited. Therefore, the door 26 completes the opening operation inthe widely opened state without being limited by the switch operatingportion 167B.

[0150] In this steering wheel W5 also, the switch operating portion 167Bis pushed by the opening door 26 and moved, and disposed in thenon-limited region. That is, according to this steering wheel W5 also,in a normal state before the door 26 is opened, the switch operatingportion 167B can be disposed near the ring surface P at a upper positionas close as possible. As a result, with this steering wheel W5 also, thedoor 26 can open widely and the operability of the switch operatingportion 167B is excellent.

[0151] In the steering wheels W2 and W5 of the second and fifthembodiments, operation direction of each operation button 169 of eachswitch operating portion 167, 167B is downward direction. When theswitch operating portion 167 or 167B is moved to the non-limited region,it is not moved downwardly. That is, when the switch operating portion167 or 167B is pushed by the door 26, the switch operating portionrotated and moved in the lateral direction so as to intersect with theoperation direction of the operation buttons 169 substantially at rightangles, and is moved to the non-limited region of the door 26.Therefore, even if the operation buttons 169 that must be operatedstrongly downward at the time of operation is disposed on the switchoperating portion 167 or 167B, the switch operating portion 167 or 167Bis less prone to move the non-limited region. As a result, in the secondand fifth embodiments, the operability of the operation buttons 169 canbe stabilized.

[0152] Although the operability of the operation buttons 169 of theswitch operating portion 167 is not excellent, the operating surface 169a may be located at a position largely lower than the ring surface Plike a steering wheel W6 shown in FIG. 20. That is, in the steeringwheel W6, the switch operating portion 167 is originally disposed in thenon-limited region below the opened door 26. According to this steeringwheel W6, even if the opening operation of the door 26 has beencompleted, the door does not come into contact with the switch operatingportion 167.

[0153] Further, in the second to sixth embodiments, three spoke typesteering wheel W2, W3, W4, W5 and W6 are described. As the second tosixth embodiments, two or four spoke type steering wheel may be used. Inthe steering wheel, the number of the doors of the pad is not limited tothree, and one or more doors may be provided.

What is claimed is:
 1. A steering wheel having an airbag apparatus,which comprises: a ring grasped at the time of steering, a boss disposedon a center of said ring, three spokes for connecting said ring and saidboss, and a space between said spokes, said steering wheel having, asconstituent parts, a steering wheel body, said airbag apparatus disposedon said boss, and a switch operating portion that is operated fromabove, said switch operating portion being disposed at least one of saidboss and said spoke, said airbag apparatus haivng an airbag folded suchthat the airbag is expand, an inflator for supplying expansion gas tosaid airbag, a pad for covering said folded airbag, and a bag holderconnected to said steering wheel body for holding said folded airbag,said inflator and said pad, said pad including three doors such that oneopening through which said airbag projects can be formed in a center ofsaid pad, each of said doors being provided at its periphery with to-beruptured portion, said door being pushed by said airbag when it isexpanded and said to-be ruptured portion is ruptured, said door openingaround a hinge disposed on the side of an outer periphery of said pad asa rotation center, said hinge of each of said doors being disposed at aposition near said space between said spokes, and on the side of anouter periphery of said pad that is lower than an portion above aholding portion held by said bag holder near said hinge, each of saiddoors being disposed in said three spaces between the spokes when saiddoor opens around said hinge as a rotation center; and said switchoperating portion being disposed on an area other than said doors and onsaid boss or said spoke that is not covered with said door when itopens.
 2. A steering wheel having an airbag apparatus according to claim1, wherein said to-be ruptured portion at a portion of the adjacentdoors is substantially T-shape as viewed from above, and has a lateralline portion disposed in the right-left direction and a longitudinalline portion extending rearward from a substantially central portion ofsaid lateral line portion, left and right opposite ends of said lateralline portion are directed to disposition directions of the front leftand right spokes of said spokes, and a rear end of said longitudinalline portion is directed to a disposition direction of said rear spokein said spoke.
 3. A steering wheel having an airbag apparatus accordingto claim 1, wherein said pad comprises a ceiling wall disposed on anupper portion and having said doors and said to-be ruptured portion, anda side wall extending downward from said ceiling wall and disposed inthe vertical direction such that said side wall is connected to said bagholder, remaining portion of said to-be ruptured portion except adjacentportions of said doors is disposed close to an inner surface of saidside wall of said ceiling wall and substantially along said side wall.4. A steering wheel having an airbag apparatus according to claim 1,wherein said folded airbag includes three clots of folding portions,each clot is disposed below each of said doors of said pad andaccommodated.
 5. A steering wheel having an airbag apparatus accordingto claim 1, wherein said pad is held by said bag holder using a rivet.6. A steering wheel having an airbag apparatus according to claim 5,wherein said bag holder includes a retaining pawl for retaining saidpad, said pad being held by said bag holder utilizing said rivet andsaid retaining pawl.
 7. A steering wheel having an airbag apparatusaccording to claim 1, further comprising an auxiliary plate having aninsertion piece to be inserted into said pad, said auxiliary plate beingfixed to said bag holder, said bag holder having a retaining pawl forretaining said pad, said pad being sandwiched between said insertionpiece and said retaining pawl and held by said bag holder.
 8. A steeringwheel having an airbag apparatus according to claim 3, furthercomprising an auxiliary plate having a limiting wall disposed on anouter surface of a portion of said side wall connected to said bagholder, said auxiliary plate being fixed to said bag holder, said bagholder having a retaining pawl for retaining said side wall, said padbeing prevented by said limiting wall from coming out from saidretaining pawl, and connected to and held by said bag holder.
 9. Asteering wheel having an airbag apparatus, which comprises: a ringgrasped at the time of steering, a boss disposed on a center of saidring, and a spoke for connecting said ring and said boss, said airbagapparatus being disposed on an upper portion of said boss, said airbagapparatus comprising an airbag that is folded such that it is expanded,and a pad for covering said folded airbag, said pad including a doorthat is pushed by said expanding airbag and opened, a switch operatingportion being disposed below said door when it is opened, said switchoperating portion being disposed in a non-limited region where anopening-completion state of said door is not limited for said door thathas completed its opening operation.
 10. A steering wheel having anairbag apparatus according to claim 9, wherein said switch operatingportion is disposed in said non-limited region when said switchoperating portion is pushed and moved by said door when it opens.
 11. Asteering wheel having an airbag apparatus according to claim 10, whereinsaid switch operating portion is provided at its upper portion with anoperation button that is pushed down for operation, and when said switchoperating portion is pushed and moved by said door, said switchoperating portion is rotated and moved in the lateral direction thatintersects with an operation direction of said operation buttonsubstantially at right angles so that said switch operating portion ismoved to said non-limited region.
 12. A steering wheel having an airbagapparatus according to claim 10, wherein said switch operating portionis lowered and moved to said non-limited region when said switchoperating portion is pushed and moved by said door.
 13. A steering wheelhaving an airbag apparatus according to claim 91, wherein said switchoperating portion is originally disposed in said non-limited region.